package collection;

import java.util.ArrayList;
import java.util.List;

/**
 * List获取子集操作：
 * List<T>要头不要尾
 */
public class ListDemo3 {
    public static void main(String[] args) {
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            list.add(i * 10);
        }
        System.out.println("list:" + list);//list:[0, 10, 20, 30, 40, 50, 60, 70, 80, 90]

        List<Integer> subList = list.subList(3, 8);//获取下标3到7的子集
        System.out.println("subList:" + subList);//[30, 40, 50, 60, 70]

        //将子集每个元素扩大10倍
        for (int i = 0; i < subList.size(); i++) {
            subList.set(i, subList.get(i) * 10);
        }
        System.out.println("subList:" + subList);//subList:[300,400,500,600,700]
        // 注意：对子集的操作就是对原集合对应元素的操作
        System.out.println("list:" + list);//list:[0, 10, 20,300,400,500,600,700, 80, 90]


        list.set(3, 1000);//将原集合对应下标为3的元素修改为1000
        System.out.println("list:" + list);//list:[0, 10, 20,1000,400,500,600,700, 80, 90]
        //原集合数据改变后，子集数据跟着变
        System.out.println("subList:" + subList);//subList:[1000,400,500,600,700]

        list.remove(0);
        System.out.println("list:"+list);//list:[10, 20,1000,400,500,600,700, 80, 90]
        //原集合长度改变后，子集将不能再进行任何操作了，若操作则发生异常，但是可以重新获取子集
        //System.out.println("subList:"+subList);
    }
}